Former cycling doper turned whistleblower Tyler Hamilton described Dr Eufemiano Fuentes as a "one-man Wal-Mart of doping" in his 2012 book The Secret Race, which detailed the use of performance-enhancing drugs in the sport.
Hamilton was among 11 former teammates who testified against Lance Armstrong during the US Anti-Doping Agency's investigation.
In his only UK interview, he gave ITV News his reaction to Armstrong finally confessing.
Tyler Hamilton, a former team-mate of Lance Armstrong who implicated him in the doping scandal, has told ITV News we're likely to see a "new Lance Armstrong" now he has confessed.
Speaking about his own experience, Hamilton said in his only UK interview, "I was a broken man two-and-a-half, three years ago, and I finally did the right thing ... telling the truth felt great. It sets you free".